The uptake of compounds plays an important role in many applications. For example, activated carbons are the current industrial standard for adsorption of ammonia for gas cleanup. Oxidation of carbon surfaces, or acid-washing, is often used to generate oxygen rich or acidic sites for ammonia sorption to improve ammonia affinity and capacity in these materials. However, even the best of these materials suffer from relatively low ammonia capacity of approximately 11-12 mmol/g. Additionally, the sites for sorption in these materials are poorly defined, and therefore the adsorption enthalpy for ammonia can vary widely across the various oxygen containing carbon sites.
For adsorption heat pump and thermal battery applications, the activated carbon-ammonia working pair has been studied for adsorption cooling. However, the ammonia capacities are too low. Ammonia exchange capacity, the amount of ammonia adsorbed and desorbed per gram adsorbent during the working and regeneration cycles, is a criterion since it ultimately dictates the amount of heat transferred in a given cycle. Additionally, the broad, poorly defined distribution of sorption sites in the activated carbon materials produces a distribution of adsorption enthalpies for ammonia, an undesirable trait that prevents full utilization of the total uptake capacity.
As another non-limiting example, molecular bromine is another industrially important raw chemicals and is used in many applications, including for the preparation of flame retardants, agricultural products, and pharmaceuticals. Unfortunately, its extreme toxicity and high corrosiveness poses a serious challenge for safe handling, storage and transportation. Despite decades of experience in mitigating these challenges, tragic accidents still occur worldwide due to leaks or explosions, making the development of recyclable materials that can enable safe handling, and on-demand delivery of bromine highly desirable
Accordingly, improved compositions and methods are needed.